The rotation and stretching of the two disks enable the flow of hybrid nanofluid in a variable porous space for thermal applications

Purpose The studied literature and other similar works for fluid flow between rotating disks have revealed that the space between two disks is either porous or non-porous but no investigation contains variable porous space between the two disks, which creates a gap in existing literature and is the main novelty in current work. Although the single disk has been used in the literature Hayat et al. (2020), but the concept of fluid flow between two disk is not focused. To fill this gap in the literature, current work addresses heat transfer and fluid flow for hybrid nanofluid (HNF) through a variable porous space between two parallel stretching disks which is the novelty in this study. Water is considered a base fluid, while TiO2 and Ag are suspended in it as nanoparticles. Design/methodology/approach The present work aims to study the HNF flow between two rotating disks for heat transfer enhancement applications using the concept of variable porous space. TiO2 and Ag nanoparticles are suspended in water to form the HNF. This variation in pores makes the fluid more flexible for the heated disks to exchange heat more efficiently, resulting in improved thermal efficiency. The variation of pores in the porous space improves the thermal efficiency of HNFs by enhancing fluid flow, enhancing nanoparticle holding and increasing interaction between fluid and nanoparticles. The main equations have been changed to dimensionless form using suitable variables. Then these equations were solved by employing the homotopy analysis method (HAM). For modeled equations, an average residual error is computed through HAM while the impacts of emerging factors on flow profiles are discussed graphically. Furthermore, engineering parameters like skin friction and Nusselt number are calculated numerically and displayed in tabular form. Findings The main equations have been changed to dimensionless form using suitable variables. Then these equations were solved by employing the HAM. For modeled equations, an average residual error is computed through HAM while the impacts of emerging factors on flow profiles are discussed graphically. Furthermore, engineering parameters like skin friction and Nusselt number are calculated numerically and displayed in tabular form. Originality/value The main equations have been changed to dimensionless form using suitable variables. Then these equations were solved by employing the HAM. For modeled equations, an average residual error is computed through HAM while the impacts of emerging factors on flow profiles are discussed graphically. Furthermore, engineering parameters like skin friction and Nusselt number are calculated numerically and displayed in tabular form.